The present invention relates to a cutting method in which the cutting precision is excellent and all possible disaster prevention measures are taken, and cutting oil used therein.
Cutting solutions are generally classified into water-soluble oil agents and water-insoluble oil agents, and they have the following characteristics, respectively.
First, a water-soluble oil agent has advantages whereby the processing precision can be increased since the cooling capability is excellent, and heating deterioration of tools can be prevented. Also, since the oil agent is used as a solution, it has an advantage whereby there is no danger of fire due to its non-flammability. However, since the agent is used as a solution diluted 10 to 50 times, in comparison with the water-insoluble oil agent, film strength is poor, and lubrication performance is also poor.
On the other hand, the water-insoluble oil agent has greater excellent effects as a cutting oil than the water-soluble oil agent whereby an excellent machined surface can be easily obtained due to excellent lubrication performance, and tools are not greatly worn. However, the water-insoluble oil agent is poorer in cooling capability and fire preventive performance than the water-soluble oil agent.
At a machining site, in accordance with an increase in rigidity of the machine, improvement in performance of tools, and improvement in machine controlling performance, the feeding speed can be increased, and the cutting area can be made larger. Therefore, the oil temperature easily rises as the cutting temperature rises, and in addition, the temperature at the cutting point also rises, whereby an ignition source area exceeding 500xc2x0 C. increases. And, the stronger an impact added, the higher the possibility of sparking, and therefore, the danger of fire increases.
Also, when the processing machine is auto-operated, sometimes broken tools remain at the machined portion, and if the next processing is applied to this machined surface, tools are forcibly pressed against this surface, and may cause excessive heating resulting in a fire.
Therefore, generally, regarding disaster prevention as important, a water-soluble oil agent is mostly used, however, regarding roughness of the machined surface and machining stability as important, sometimes a water-insoluble oil agent is used, and in this case, a situation where the machine is damaged by fire and must be discarded, or personal injury (burns) is caused occurs.
In view of the current circumstances where machining works show a tendency toward labor saving and automation, it is extremely preferable that machining stability can be pursued. without worrying about disaster prevention if possible. Herein, it can be considered that an emulsifier is added to the water-insoluble cutting oil to be in a water containing condition, however, the contained moisture immediately disappears and flammability revives in actuality. For example, when the oil is used for a lathe, a water content of 10% in the morning changes to less than 1% by evening. Also, when an emulsifier is added to the water-insoluble cutting oil, the lubrication performance as a water-insoluble cutting oil is lost due to an influence from the emulsifier.
The invention is made in view of the above problems, and the themes thereof are to enable stable machining by using a water-insoluble oil agent, and provide a machining method with sufficient measures taken against disaster, and a cutting oil to be used in machining.
In order to achieve the above themes, in claim 1 of the invention, a cutting method in which a solution is sprayed or jetted to the machining portion when machining by use of a water-insoluble cutting oil is provided, wherein recovered liquid is collected and stored in a recovery tank, based on the specific gravity difference, the water-insoluble cutting oil and other solutions are separated from each other, and are re-used. In the invention, for convenience, the words of cutting and solution are used, however, substantially, cutting includes grinding and other similar machining, and solution includes water (and so forth).
In the invention, when machining such as cutting and grinding, since a solution is sprayed or jetted to the machining portion, the cooling effect is excellent, and there is no danger of fire even if the water-insoluble cutting oil is used. Also, the machining precision can be increased due to a high cooling effect. Also, spraying of a solution is a concept including pouring of mist or a shower of the solution.
(A) Water-insoluble Cutting Oil of the Invention
The water-insoluble cutting oil generally means the first type cutting oil agent (No. 1 through 6) made from mineral oil and animal/botanical oil, or mineral oil and ester oil, and the second type cutting oil agent (No. 1 through 6, 11 through 17) in which an additive is added to the first type cutting oil agent, and if taking into account separativeness from a solution, an oil with a small acid value and a small content of saponified substance is preferable, and the acid value of the additive to be used is preferably 1 KOH mg/g or less.
Concretely, the oil is composed from a combination of proper amounts of highly refined mineral oil, chlorinated paraffin, and polysulfide. For the combination, only mineral oil need be used, or a liquid mixture of mineral oil and chlorinated paraffin, mineral oil and polysulfide, or mineral oil, chlorinated paraffin, and polysulfide can be used. If an oily effect is necessary, a slight amount of oils and fats whose acid value is 1 KOH mg/g or less can be added.
(B) Solution of the Invention
Also, generally, a solution of water-soluble cutting agent, a solution containing an anticorrosive, and a cleansing agent solution correspond to the solution of the invention, and an alkali liquid can be used even if it has little difference in anticorrosive performance, and moreover, it is preferable that the liquid has excellent separativeness from the water-insoluble cutting oil and hardly forms a middle layer. Specifically, {circle around (1)} a solution of 0.1 through 2% of triethanolamine, {circle around (2)} a solution diluted 30 times of a water-soluble cutting oil containing approximately 25 through 30% of triethanolamine, approximately 8 through 15% of a medium-chained fatty acid, and approximately 40 through 60% of water as the principal ingredients, and {circle around (3)} a solution containing 0.5% or less of a surfactant (negative ionic, positive ionic, amphoteric ionic, or nonionic surfactant including soap) are applicable.
The water-insoluble oil agent and solution are collected in one recovery tank in a dispersed and mixed condition, and are separated based on the specific gravity difference. Since tools may be chipped due to massive moisture if the viscosity of the water-insoluble oil agent increases in accordance with the water content, in order to maintain the original characteristics of the oil agent, the water content rate must be set to at least 50% or less, and preferably, 5% or less. Therefore, it is preferable that the recovery tank has a capacity enabling 5 minutes or more of collected liquid storing time.
As the operating environment of the invention, in a case of slight amounts of shavings, it is preferable that the water-insoluble oil agent and solution which are separated in the recovery tank from each other are stored in separate storing tanks, and then supplied to the cutting machine.
Claim 2 of the invention relates to a cutting method in which a water-insoluble cutting oil or water-soluble cutting oil is selectively used in accordance with machining, wherein the recovered liquid is collected and stored in one recovery tank, separated into water-insoluble cutting oil and water-soluble cutting oil on the basis of the specific gravity difference, and are re-used.
In the invention, since optimum cutting or grinding suitable for the object to be machined and machining condition can be performed, for example, when machining for which lubrication is regarded as important, the water-insoluble cutting oil may be used. In this case, since lubrication is sufficient, preferable cutting can be performed, and in addition to this effect, other effects can be obtained whereby rust and offensive smells are prevented. Also, in order to completely eliminate the danger of fire, the method of claim 1 can be used at the same time.
On the other hand, in a case where cooling performance must be regarded as important, or viscosity of oil after machining is not preferable, the water-soluble cutting oil may be used. In this case, advantages of the water-soluble cutting oil are provided such that there is no danger of fire, the machined object is not sticky, the machine is not contaminated by the oil, cooling performance is sufficient, and so on.
As the water-insoluble cutting oil and water-soluble cutting oil to be used, oils described in the above (A) and (B) are preferable.
Claim 3 of the invention relates to a cutting method in which a water-insoluble cutting oil is used in a water containing condition without using an emulsifier, wherein the water-insoluble cutting oil is a mineral oil or a liquid mixture. containing chlorinated paraffin or polysulfide and mineral oil as the principal ingredient, and the water-insoluble cutting oil after being used is collected and maintained in a condition containing approximately 4% through 20% of water. According to the examination by the present inventor, it has been confirmed that, in a case of a water content of 4% or more, flammability can be suppressed, and in a case of a water content of 20% or less, characteristics of the water-insoluble cutting oil are not lost.
In order to use the water-insoluble cutting oil in a water. containing condition, for example, a water-insoluble cutting oil and water are mixed together, and then separated from each other, whereby the obtained water-insoluble cutting oil can be used. However, in the invention, since a mineral oil or a liquid mixture of chlorinated paraffin or polysulfide and a mineral oil is used, the water content may become 4% or less for excellent separativeness from water. Therefore, in such a case, the inside of the storing tank is slowly stirred, or by using a slight amount of a surfactant, the water content of 4% or more can be maintained. Also, a countermeasure can be taken by watering on the periphery of the machining portion when cutting.